When using an electromagnetic wave having a short wavelength of several tens of nm or less, a refractive index difference for the electromagnetic wave between different materials is very small, so the total reflection angle is very small. Therefore, to control electromagnetic waves including X-rays, a large-scale spatial optical system has been used, and is still mainly used. One of the main components included in the spatial optical system is a multilayer film reflecting mirror in which materials having different refractive indices are alternately laminated. The multilayer film reflecting mirror has various functions such as beam shaping, spot size conversion, and wavelength selection.
Different from such a spatial optical system which is mainly used, a conventional X-ray waveguide tube such as a poly-capillary confines X-rays in the tube and propagates the X-rays. In recent years, an X-ray waveguide is studied, which confines electromagnetic waves in a thin film or a multilayer film and propagates the electromagnetic waves, in order to downsize and enhance the optical system. Specifically, a thin film waveguide is reported in which a guiding layer is sandwiched by a two-layer one-dimensional periodic structure (see NPL 2). Further, an X-ray waveguide is reported in which a plurality of thin film X-ray waveguides that confine X-rays by total reflection are laminated and disposed (see NPL 1).